Quantumscape prototypes 24-layer solid-state cells

Volkswagen’s partner for solid-state batteries, Quantumscape, claims to make bold strides in its Q2 letter to shareholders. The company says it is now successfully building and testing prototype 24-layer cells – up from 16 layers just a few months ago.

Solid-state battery development appears accelerating at Quantumscape that said, they were “building on this momentum”. The company suggests, the 24-layer cells showed similar early capacity retention behaviour to the company’s earlier single-, four-, 10- and 16-layer cells, first released in 2020. The last update came in May this year on 16-layer cells. Already at the time, Quantumscape said they were working towards more layers.

Another key target this year, is for A-samples to go out to carmakers – the company now counts six (prospective) OEMs among its clients but has not disclosed names, apart from the Volkswagen Group.

“Our collaboration with Volkswagen Group’s engineering teams has intensified in recent months, with regular technical and product development meetings; their expertise has proved especially valuable as we build competence in mass manufacturing,” says Quantumscape.

For the remaining A-sample clients, the company just said, that these include global top-10 manufacturers by revenue to premium performance and luxury automakers, encompassing both pure EV and conventional OEMs.

In today’s letter, Quantumscape added that the precise definition of an A sample would vary by customer, “delivering any such cell to an automotive customer is a high bar and remains one of our key goals for the year.”

Talking about form, at present, the 24-layer cells are being tested in various formats, including early variants of QuantumScape’s “proprietary format under development”. The design was to accommodate the expansion and contraction characteristics of Li-metal batteries during charge and discharge. Quantumscape adds, that they have built and tested many cells of varying layer counts in this new format, including some that have achieved over 600 cycles and are still cycling. This is up from 400 cycles in released data from earlier this year. Back then, the solid-state lithium metal battery cells retained more than 80 per cent of their initial energy after 400 cycles of 15-minute fast charges.

The company also reported advances in separator manufacturing and the implementation of its next-gen catholyte. In Quantumscape cells, a ceramic separator isolates the cathode from the anode, allowing the company to experiment with otherwise incompatible materials. The improved design offers better low-pressure performance, improved low-temperature behaviour at -30 degrees Celsius, better high-rate support, and improved cell reliability compared to the first-generation catholyte, the company says.

They are also working to further improve manufacturing processes, especially since running into issues regarding impurities or faults during production. Separator production and cell assembly are the main parts and QuantumScape will make the A and B samples on the QS-0 pilot line in San José where the company has entered Phase 2. This new line benefits from six times more floorspace for cell assembly, expand automation and in-line metrology, and add more cell assembly lines as Quantumscape continue to scale production. In addition, production is already more automated. The automated cell stacker now completes the operation in 30 seconds instead of five minutes. This adds of course consistency, as the process is always carried out in the same way and deviations are smaller.

B-sample cells are still scheduled to enter testing in 2023. These differ from the A-samples, among other things, in that production processes from series production are already being used. C-samples will come in the earliest 18 months after.

quantumscape.com (letter to shareholders), greencarcongress.com